KINETICS Pipe & Duct Seismic Application Manual

Transcription

1 I8. Why are Stiffeners Needed? rod stiffeners are used to prevent the buckling of the hanger rods under the compressive reaction loads during an earthquake. Buckling is very difficult to predict, and depends on many factors such as, hanger rod length, hanger rod size, the dead load carried by the hanger rod, the horizontal seismic ces applied to the pipe or duct, and the seismic restraint installation angle. Buckling is also a very dangerous type of failure. It occurs in long slender structural members under compressive load, and it occurs at loads far less than those required to yield the material in the structural member. It is impractical the installing contractor to be able to m the calculations needed to determine if rod stiffeners are required, and to select the pro stiffener element. This section will provide the contractor with some basic tools that can be used to visually determine the need rod stiffeners. Then the matter can be referred to the engineer of record the system to have the pro calculations done using the on-line web tools provided by Kinetics Noise Control. I8.2 When are Stiffeners Needed?. For Seismic Design Categories A & B no seismic restraints, and thus, no rod stiffeners are required pipe and duct. 2. For Seismic Design Categories C & D, and cable/strut installation angles no greater than 45 as measured from the horizontal, use Tables I8. through I8.2. In these tables, N.S.R. means that no rod stiffener is required the specified hanger rod size and restraint spacing. For all other cases the maximum Unstiffened, or critical, hanger rod length is given single hanger rod supported pipe & duct, and trapeze bar supported pipe and duct. 3. For Seismic Design Categories C & D, seismic restraint installation angles greater than 45 as measured from the horizontal, and or spacings less than 0, assume that rod stiffeners will be required. PAGE of 6 SECTION I8.0

2 4. For Seismic Design Categories E & F rod stiffeners will be required almost all cases, consult with the engineer of record. Table I8-; Maximum Unstiffened Pipe & Duct, Seismic Design Category C, Spacing is 0, Restraint Spacing is 0, and Restraint Installation Angle is 45 3/8 5 N.S.R. N.S.R. /2 3 N.S.R. N.S.R. 5/8 23 N.S.R. N.S.R. 3/4 50 N.S.R. N.S.R. 7/8 99 N.S.R. N.S.R. 72 N.S.R. N.S.R. /4 40 N.S.R. N.S.R. PAGE 2 of 6 SECTION I8.0

3 Table I8-2; Maximum Unstiffened Pipe & Duct Seismic Design Category C, Spacing is 0, Restraint Spacing is 20, and Restraint Installation Angle is 45 3/8 5 N.S.R. 34 /2 3 N.S.R. 39 5/8 23 N.S.R. 47 3/4 50 N.S.R. 48 7/8 99 N.S.R N.S.R. 47 /4 40 N.S.R. 49 Table I8-3; Maximum Unstiffened Pipe & Duct Seismic Design Category C, Spacing is 0, Restraint Spacing is 30, and Restraint Installation Angle is 45 3/8 5 N.S.R. 9 /2 3 N.S.R. 22 5/8 23 N.S.R. 27 3/4 50 N.S.R. 27 7/8 99 N.S.R N.S.R. 27 /4 40 N.S.R. 28 PAGE 3 of 6 SECTION I8.0

4 Table I8-4; Maximum Unstiffened Pipe & Duct Seismic Design Category C, Spacing is 0, Restraint Spacing is 40, and Restraint Installation Angle is 45 3/ / / / / / Table I8-5; Maximum Unstiffened Pipe & Duct Seismic Design Category C, Spacing is 0, Restraint Spacing is 60, and Restraint Installation Angle is 45 3/8 5 9 / / / / / PAGE 4 of 6 SECTION I8.0

5 Table I8-6; Maximum Unstiffened Pipe & Duct Seismic Design Category C, Spacing is 0, Restraint Spacing is 80, and Restraint Installation Angle is 45 3/ / / / / / Table I8-7; Maximum Unstiffened Pipe & Duct Seismic Design Category D, Spacing is 0, Restraint Spacing is 0, and Restraint Installation Angle is 45 3/8 5 N.S.R. N.S.R. /2 3 N.S.R. N.S.R. 5/8 23 N.S.R. N.S.R. 3/4 50 N.S.R. N.S.R. 7/8 99 N.S.R. N.S.R. 72 N.S.R. N.S.R. /4 40 N.S.R. N.S.R. PAGE 5 of 6 SECTION I8.0

6 Table I8-8; Maximum Unstiffened Pipe & Duct Seismic Design Category D, Spacing is 0, Restraint Spacing is 20, and Restraint Installation Angle is 45 3/8 5 N.S.R. 9 /2 3 N.S.R. 22 5/8 23 N.S.R. 27 3/4 50 N.S.R. 27 7/8 99 N.S.R N.S.R. 27 /4 40 N.S.R. 28 Table I8-9; Maximum Unstiffened Pipe & Duct Seismic Design Category D, Spacing is 0, Restraint Spacing is 30, and Restraint Installation Angle is 45 3/ / / / / / PAGE 6 of 6 SECTION I8.0

7 Table I8-0; Max. Unstiffened Pipe & Duct Seismic Design Category D, Spacing is 0, Restraint Spacing is 40, and Restraint Installation Angle is 45 3/8 5 9 / / / / / Table I8-; Max. Unstiffened Pipe & Duct Seismic Design Category D, Spacing is 0, Restraint Spacing is 60, and Restraint Installation Angle is 45 3/ / / / / / PAGE 7 of 6 SECTION I8.0

8 Table I8-2; Max. Unstiffened Pipe & Duct Seismic Design Category D, Spacing is 0, Restraint Spacing is 80, and Restraint Installation Angle is 45 3/8 5 7 / / / / / I8.3 How are Stiffeners Selected and Installed? The sizing of the rod stiffeners may be accomplished using the techniques outlined in Section S8.0 and Appendices A5. through A5.8 of this manual. Section S8.7 outlines the requirements and procedure using the on-line web Stiffener program provided by Kinetics Noise Control. Sizing rod stiffeners is not a task that should be attempted by the installing contractor in the field, and should be med by a qualified design professional. The following basic rules will help to determine the need rod stiffeners.. stiffeners only need to be used on hanger rods that carry the reaction loads from seismic restraints. 2. When determining the requirements rod stiffeners, consider both the transverse (T) and Longitudinal (L) restraints on the run of pipe or duct. Remember, the longitudinal (L) restraints are typically spaced further apart than the transverse (T) restraints and could PAGE 8 of 6 SECTION I8.0

9 require rod stiffeners when the transverse (T) restraints did not, or require larger rod stiffeners when the transverse (T) restraints also required rod stiffeners. 3. Where hanger rods carry the loads from both Transverse (T) and Longitudinal (L) seismic restraints, the rod stiffeners need to be sized to carry only the reaction loads from the more severe case. Kinetics Noise Control has designed a series of clamps that are used with standard rolled structural angle to create a rod stiffener system, which are shown in Figure I8-. The model KHRC-B clamp has been designed to work with hanger rods from 3/8 to -/8 in diameter. The model KHRC-C clamp is use with hanger rods from 3/8 to -/8 in diameter. Table I8-3 shows the rolled structural angles recommended use as rod stiffeners by Kinetics Noise Control, and the model KHRC stiffener clamps to be used with each angle size. The analysis outlined in Section S8.0, and Appendix A5., or the on-line web based Stiffener program will indicate which angle and clamp are to be used and how many clamps will be required to proly stiffen the hanger rod. PAGE 9 of 6 SECTION I8.0

10 UNC x 2 Hex Head Bolt UNC Hex Jam Nut KINETICS KHRC-B UNC x 2 2 Hex Head Bolt UNC Hex Jam Nut KINETICS KHRC-C Model KHRC-B Model KHRC-C Figure I8-; Kinetics Noise Control Model KHRC Stiffener Clamps Use with Rolled Structural Angle PAGE 0 of 6 SECTION I8.0

11 Table I8-3; Stiffener Angle Code Designation and Model KHRC Stiffener Clamps Stiffener Code AISI Angle Designation Stiffener Clamp Model A L x x /8 B L -/4 x -/4 x /4 C L -/2 x -/2 x /4 D L -3/4 x -3/4 x /4 E L 2 x 2 x /4 F L 2 x 2 x 3/8 G L 2-/2 x 2-/2 x /4 H 2 L 2-/2 x 2-/2 x 3/8 I 2 L 2-/2 x 2-/2 x /2 KHRC-B KHRC-C The Stiffener Code is used by the Kinetics Noise Control Stiffener Program streamline the specification of the rod stiffener. 2 These rod stiffener angles may be used with the Kinetics Noise Control Model KHRC-C rod stiffener clamp. Not all hanger rod sizes may work with these arrangements. Check with Kinetics Noise Control Engineering your particular application. The basic installation of the rod stiffener clamps is detailed in Figure I8-2, and typical rod stiffener installations are shown in Figures I8-3 through I8-6. PAGE of 6 SECTION I8.0

12 Stiffener Angle Jam Nut KNC KHRC-B Stiffener Clamp.) Hold rod stiffener angle against hanger rod. 2.) Slide all required clamps over angle and hanger rod. 3.) Position top & bottom clamps 4 away from ends of angle & tighten clamp bolts 4.) Equal space and tighten remaining clamps. Clamp Bolt.) Center clamp bolt on hanger rod. 2.) Tighten clamp bolt securely. 3.) Tighten jam nut against clamp body. Figure I8-2; Basic Installation of Kinetics Noise Control Model KHRC Stiffener Clamps PAGE 2 of 6 SECTION I8.0

13 Remaining Clamps Equally Spaced Stiffener Angle to Rest on Clevis Nut or Kinetics KSCA Bracket Figure I8-3; Typical Stiffener Installation Non-Isolated Clevis Hung Pipe PAGE 3 of 6 SECTION I8.0

14 Remaining Clamps Equally Spaced See Section S.0 Rule #8 Stiffener Angle to Rest on Clevis Nut or Kinetics KSCA Bracket Figure I8-4; Typical Stiffener Installation Isolated Clevis Hung Pipe PAGE 4 of 6 SECTION I8.0

15 4 4 Typ 2 Typ Remaining Clamps Each to be Equally Spaced Stiffener Angle to Rest on Nut. Position Clamp to Miss Restraint Figure I8-5; Typical Stiffener Installation ed Pipe & Duct Two s PAGE 5 of 6 SECTION I8.0

16 Only s with Restraints Require a Stiffener 4 2 Remaining Clamps to be Equally Spaced Position Clamp to Miss Restraint Figure I8-6; Typical Stiffener Installation ed Pipe & Duct One PAGE 6 of 6 SECTION I8.0